1. Field of the Invention
This invention relates to a data recording/reproducing apparatus of spiral track system with kick back control.
2. Description of the Prior Art
A data, recording/reproducing apparatus of spiral track system with kick back control which changes its track-turn position of the read/write head in accordance with a desired address, is known. FIG. 9 is a block diagram of such prior art recording/reproducing apparatus which comprises: a drive motor 2 for rotating a disc having a spiral track; a servo circuit 4 for driving the motor 2 and a read/write head (pick up) 3; a controller 5 for controlling a head position and rotation of the motor; the microprocessing unit (MPU) 8 receiving and sending data from/to an external computer unit 52 through an interface circuit 7; a data processing unit including a direct memory access (DMA) controller 10, a memory 9, an error correction circuit (ECC) 11, a formatter 14, and a read/write (r/w) signal processing circuit 6. In write mode, data received from the external computer unit 52 is stored in the memory 9 using the DMA controller 10. The ECC 11 adds error correction codes to the received data and sends them to the formatter 14 for formatting the data. The formatter 14 sends the data to the read/write processing circuit 6. The formatter 14 also checks errors of writing by checking address read from the disc 1. The read/write signal processing circuit 6 writes the data and other additional information, for example, error correction codes on the disc 1 along a spiral track by intermittently turning on a laser provided in the read/write head 3. In read mode, data is read by the read/write head 3 and received by the read/write signal processing circuit 6. The read data is deformatted by the formatter 14 which checks read errors and sends the result to the microprocessing unit 8 as an error signal.
When an error occurs during reading/writing data, the microprocessing unit 8 sends a command to the controller 5 to read/write again the sector just read/written. The microprocessing unit 8 sends the command in accordance with a flow chart shown in FIG. 10.
In FIG. 10, the microprocessing unit 8 starts to read or write at step 101. In step 103, the microprocessing unit 8 detects a read/write error signal from the formatter 14. In step 104, the microprocessing unit 8 sends the command for changing one track-turn (the spiral defined by one rotation of the disc 1) position of the head 3 back, i.e., kick back, to the controller 5. Then, the formatter 14 waits for the address just read/written. Therefore, it takes a relatively long interval to respond to the command because it takes a long time to perform an address calculation to determine how many track turns the position of the head 3 should be changed and to calculate the rotational velocity. In other words, timing relation between error detection and changing head position needs to be quite precise even if the head position is changed by only one track turn. In the following step 105, the microprocessing unit 8 waits completion of access of the head 3. An interval of this waiting is long because the controller 5 determines to move the head 3 by one track turn back after calculation of address of the desired track turn and the present address, as mentioned above.
Moreover, in the above-mentioned apparatus, there is a drawback that it is impossible to perform writing and verifying operation continuously. The verification operation is performed in accordance with a flow chart of FIG. 11. In FIG. 11, the microprocessing unit 8 starts write/verification in step 201. At first, the microprocessing unit 8 writes data in accordance with the steps shown in FIG. 10 in the following step 202. In the succeeding step 203, the microprocessing unit 8 sends an access command to the controller 5 so as to change track-turn position of the head 3 by two track turns back to of access of the head 3 to the top sector. In the following step 204, the microprocessing unit 8 detects completion of access of the head 3 by detecting an address of the top sector. After access of the head 3, in step 205, the microprocessing unit 8 verifies data read according to the flow of FIG. 10 by comparing the data with stored data which was written on the disc 1. Therefore, it takes a relatively long interval to of access of the head to the top sector where data has been just written. In other words, the time interval necessary for kick back operation is long. The reasons are as follows:
Unit length of recording and reading data is carried out at every track turn when verification is carried out so as to move the head by two track turns. Because if the head 3 is moved only one track turn, it cannot access the top sector which is just written because of the time interval necessary for moving the head. Therefore, there is the drawback that during verification, the head cannot kick back to the sector which has just been written.